Recently I went to els Ports (Beseit/Tortosa) in Catalonia to do a Common Bird Census which I have been doing for the last 5 years or so for the Institut Català d’Ornitologia. It’s a wonderfully scenic 3 km transect following the course of a river gorge. Birds are not that abundant in the gorge itself although the surrounding olive groves and pine woods make up for that. Usual species include Firecrest (also Goldcrest in the winter), Coal Tit, Bonelli’s Warbler (summer), Sardinian Warbler, Blue Rock Thrush and more. For the last two transects I’ve seen a Peregrine Falcon sitting in exactly the same place, the ever-radiant Kingfisher and a dozen or so Griffon Vultures.
What I haven’t seen for the last couple of years is the Bonelli’s Eagle. Now that’s a surprise and a shame because a territorial pair has one of its known nests in view of my transect, and 2 years ago these birds used to offer wonderful views of synchronised flying in the breeding season. Last year I scanned the area around their nest but only saw two Griffon Vultures. The same happened yesterday.
It’s a known fact that the recent recovery of Griffon Vultures has been to the detriment of Bonelli’s Eagles in some places where the two species coincide. The Griffon Vultures oust the Bonelli’s Eagles and take over their nests. Apparently the same has happened, for example in Extremadura, with Golden Eagles ousting the Bonelli’s Eagles too.
This is not meant as a harangue against Griffon Vultures. Bonelli’s Eagles (less than 750 pairs in Spain of 1,000 in all of Europe) are under threat from other sources which have a greater impact on their populations than competition from other birds of prey: electrocution, habitat fragmentation and loss, shooting and disturbance.
But it does annoy me that I can no longer enjoy the double treat of the scenery of els Ports and the spectacle of Bonelli’s Eagles.